The English Standard Version of the Bible translates the phrase in question as "you have given me an open ear", and notes that literally the phrase means "ears you have dug for me".

So my question is, are we just talking about an open ear in the sense of a willingness to listen to HaShem? Or is there more to it? An alternative translation I've seen reads "my ears you have pierced". Is this valid, and if so, does it lend some more context?